Silicon metal, including high silicon alloys, are useful in applications where an acid-resistant material is needed. Additionally, silicon and high silicon alloys which have been rendered electroconductive by the presence of a dopant are particularly desirable for electrochemical applications, e.g., electrode substrates. However, in such applications, silicon must frequently be cast into complex and precise shapes. This gives rise to a complication because silicon and silicon alloys containing high amounts of silicon, e.g., in excess of 97 weight percent silicon and even 95 weight percent silicon have a positive coefficient of volumetric expansion upon solidification. By coefficient of volumetric expansion upon solidification is meant ((V.sub.s -V.sub.L)/V.sub.L).times.100 where V.sub.s is the volume of the solid silicon, and V.sub.L is the volume of the liquid silicon.
The positive coefficient of expansion upon solidification results in the bulging of the casting as the expanding silicon presses nonuniformly against the walls of the ingot mold. In electrochemical applications, e.g., electrodes, a high degree of dimensional uniformity is required. As a result, the castings must be cut, sawed, or similarly mechanically worked in order to provide dimensional uniformity.
One attempt at solving this problem has been to provide alloys of silicon containing less than 97 weight percent silicon and preferably less than 95 weight percent silicon. This provides a lower volumetric coefficient of expansion upon solidification. While this method has been successful in reducing the volumetric coefficient of expansion upon solidification, the corrosion resistance of the silicon alloy is not enhanced thereby, and may even be deleteriously effected.